The present invention relates to a laser surveying apparatus capable of forming a measuring reference line and a reference plane by laser light, and particularly to a laser surveying apparatus capable of forming a reference line and a reference plane each inclined a predetermined angle toward a horizontal plane as well as a horizontal reference line and a reference plane.
As conventional gradient-settable rotatable laser systems, there are known one having a structure wherein a laser projection unit is supported by gimbals or a spherical surface, and one having a stricture in which a laser projection unit is supported on vertical and horizontal axes.
A description will now be made of one having the structure in which the laser projection unit is supported by the spherical surface, based on FIG. 10. A laser projection unit 9100 is supported by a spherical surface and is constructed so that laser light is turnably applied onto a reference plane from a rotating irradiator 9200 provided in the laser projection unit 9100. Incidentally, the rotating irradiator 9200 is driven by a motor 9250.
The laser projection unit 9100 is constructed so as to be inclinable in one direction or two directions by moving an arm 9300 extending in intersecting two directions upwards and downwards by an up-down mechanism driven by a motor 9350. The laser projection unit 9100 is leveled by two gradient sensors 9410 and 9420 formed in a main body. Further, the laser projection unit 9100 is set so as to be inclined in a predetermined direction after the leveling thereof.
This gradient setting can be done by converting outputs produced from the two gradient sensors 9410 and 9420 to the number of pulses and driving the motor 9350 based on a computed angle, for example. Incidentally, a suitable gradient detector can be adopted. If the laser projection unit 9100 is inclined in one direction alone, then a surface or plane inclined toward a predetermined direction can be formed. If the laser projection unit 9100 is inclined in two directions, then a combined inclined surface can be formed.
A description will next be made of the structure in which a laser projection unit 9100 is supported by vertical and horizontal axes, based on FIG. 11. The present structure comprises a mount unit 9500 rotated about a vertical axis, and the laser projection unit 9100 rotated about a horizontal axis on the mount unit 9500. A rotating irradiator 9200 is provided on the laser projection unit 9100 so that laser light can be turnably applied onto a reference plane. Further, the laser projection unit is leveled by suitable leveling means in a manner similar to the structure in which the laser projection unit is supported by the spherical surface.
In the structure in which the laser projection unit 9100 is supported on the vertical and horizontal axes, the mount unit is rotated in a predetermined direction in such a manner that the direction of rotation of the laser projection unit 9100 coincides with a sloping direction. After the rotation of the mount unit, the laser projection unit 9100 is inclined to a predetermined tilt angle so as to perform gradient setting.
Incidentally, the combined inclined surface can be formed by performing an arithmetic operation from two-way gradient data and inclining the laser projection unit in a direction determined based on the result of operation.
However, the conventional laser surveying apparatus has a problem in that although no errors are produced when a rotatable shaft of a gradient setting device is turned with an ideal arbitrary axis as the center, an axial backlash for providing a smooth rotation is actually required and a converted value of an angle corresponding to the axial backlash will result in a gradient error.
Thus, there has been a strong demand for the appearance of a laser surveying apparatus capable of reducing a gradient error produced due to an axial backlash and improving gradient setting accuracy.
Further, the rotatable laser system supported by the spherical surface has a problem in that while relatively high-accuracy setting is allowed because a basic structure for setting a gradient or inclination is simple, it is not suitable for high-gradient setting because a structural limitation is imposed to the set gradient.
Moreover, the rotatable laser system supported on the vertical and horizontal axes has a problem in that although the setting of a high gradient is relatively easy, high working accuracy is required because many errors are accumulated in the rotatable shaft as described above, thus causing an increase in cost.